The present invention relates to hand operated offset shears or snips for cutting sheet material.
When sheet metal or similar material is cut with conventional snips, one or both edges of the cut sheet material may interfere with the body of the snips, making it difficult to advance the snips into the sheet material and distorting the cut edges. This interference is greatest when cutting irregular shapes. Accordingly, conventional snips are often supplied in mirror image configurations particularly adapted for either left-hand or right-hand turning cuts. Also, when conventional snips are used to cut thick, tough or stiff material, the sheet material may tend to slide away from the blades as they are closed, decreasing the efficiency of the cutting. Further, conventional snips may require long handles and substantial force to be exerted by the operator in order to cut many sheet materials.
As illustrated by U.S. Pat. No. 2,264,840, one approach to decreasing the interference of the cut sheet material with the body of the snips is to offset the cutting surfaces with respect to the shank portions of the snips such that the cut sheet material passes to one side of the shank portions. Also illustrated therein is the practice of extending the cutting blades laterally approximately at right angles to the plane of operation of the shanks. This configuration facilitates the advancement of the snips into the sheet material by reducing the extent to which the cut sheet material must be spread vertically to pass above and below the lower blade, thereby decreasing the tendency of the sheet material to slide away from the cutting surfaces. More recently, a link arrangement, as shown in U.S. Pat. No. 3,587,173, has been proposed to reduce the force required by the operator to cut heavy sheet materials.
As with conventional snips, available offset snips generally can be used only in cutting curves either in the left-hand or right-hand direction, thus requiring other offset snips having a mirror image configuration when curves must be made in the other direction. The laterally extending blades of available offset snips must be carefully ground and aligned during manufacture and, generally, cannot be conveniently reground if they become dull or damaged. Abuse of the blades by cutting wire or similar materials may render the snips useless for cutting sheet material. Accordingly, a need exists for improved offset snips which can be easily resharpened if the blades become dull or damaged. Further, there is a need for an improved handle configuration making the offset snips more convenient to use when cutting heavy sheet material.
It is therefore an object of the present invention to provide improved offset snips which can cut sheet material in both left-hand and right-hand curves without being impeded by interference of the cut material with the body of the snips.
It is a further object of the present invention to provide improved offset snips in which the cutting surfaces may be conveniently and economically resharpened if the cutting surfaces become dull or damaged.
It is a further object of the present invention to provide improved offset snips having means for cutting wire and the like, thereby eliminating the need for a second tool and reducing abuse of the sheet material cutting surfaces of the offset snips.
It is a further object of the present invention to provide improved offset snips having locking means for conveniently locking the offset snips in a closed position when the offset snips are not in use.
It is still a further object of the present invention to provide improved offset snips having handles which can more easily be grasped when the snips are in the open position and more easily forced to the closed position.